A phase III trial (SOLO2/ENGOT-Ov21) has shown improved progression-free survival with an olaparib tablet formulation vs placebo as maintenance therapy in patients with BRCA1/2-mutant platinum-sensitive relapsed ovarian cancer. These study results were reported by Eric Pujade-Lauraine, MD, of the Université Paris Descartes, and colleagues in The Lancet Oncology. A capsule formulation is currently approved in the United States; the new tablet formulation could reduce the total daily pill burden from 16 capsules to 4 tablets.

In the double-blind trial, 295 patients with relapsed high-grade serous ovarian cancer or high-grade endometrioid cancer who had received at least 2 lines of previous chemotherapy regimens were randomized 2:1 between September 2013 and November 2014 to receive olaparib at 300 mg/d (two 150-mg tablets twice daily; n = 196) or matching placebo tablets (n = 99). Randomization was stratified by response to previous platinum chemotherapy and length of platinum-free interval. The primary endpoint was investigator-assessed progression-free survival in the intention-to-treat population. The trial is ongoing.

Survival and Adverse Events

Median follow-up was 22 months. Median progression-free survival was 19.1 months in the olaparib group vs 5.5 months in the placebo group (hazard ratio [HR] = 0.30, P < .0001). Overall survival data are not yet mature (24% of planned events for analysis); median overall survival has not been reached in either group, with death occurring in 23% vs 27% (HR = 0.80, P = .43).

The most common grade ≥ 3 adverse events in the olaparib group were anemia (19% vs 2% of the placebo group), fatigue/asthenia (4% vs 2%), and neutropenia (5% vs 4%). Serious adverse events occurred in 18% vs 8%, with the most common in the olaparib group being anemia (4%), abdominal pain (2% patients), and intestinal obstruction (2%). One patient in the olaparib group died of an adverse event considered related to treatment (acute myeloid leukemia).

The investigators concluded: “Olaparib tablet maintenance treatment provided a significant progression-free survival improvement with no detrimental effect on quality of life in patients with platinum-sensitive, relapsed ovarian cancer, and a BRCA1/2 mutation. Apart from anaemia, toxicities with olaparib were low grade and manageable.”